B ) Determine the balance point of the bridge above if R and S are interchanged.
C ) What happens if the galvanometer and cell are interchanged at the balance point of the bridge? Would the galvanometer show any current?
Answer –
( a ) Let L 1 denote the balance point from end A ,
From the question statement, L 1 = 39.5 cm
Resistance of the resistor S = 12.5 Ω
Now, the condition for the balance is given by the equation –
\[\frac{R}{S}=\frac{100-{{L}_{1}}}{{{L}_{1}}}\]
\[\therefore R=\frac{100-{{L}_{1}}}{{{L}_{1}}}\times S=\frac{100-39.5}{39.5}\times 12.5\]
\[R=8.2\Omega \]
(b) when R and S are interchanged, then the lengths also gets interchanged.
Hence, the length changes to
L = 100 – 39.5 = 60.5 cm
(c) The position of the balance point remains unchanged if the galvanometer and the cell are swapped. As a result, there will be no current on the galvanometer.